1. Field of the Invention
This invention relates to a thermal transfer recording medium and more particularly to a thermal transfer recording medium capable of obtaining an excellent color dye transfer image without lowering the resolving power of the image even when using a sheet of plain paper of a low surface smoothness.
2. Description of the Prior Art
A thermal transfer recording medium has so far been used as a recording medium through which an image is transferred to and formed on such a recording sheet as a sheet of plain paper by the use of a thermal printer, a thermal facsimile apparatus or the like. It has been well known that such a thermal transfer recording medium as mentioned above has at least one coloring agent containing layer on the support of the recording medium and that such a coloring agent containing layer includes, for example, a layer containing a coloring agent comprising such a dye as a pigment and a thermally fusible material, and the like. And, as for such a support as mentioned above, there have been used a variety of films excellent in surface smoothness and in dimensional stability so as to obtain an excellent reproducibility in a dye transfer image produced of a coloring agent containing layer coated on the support.
A dye transfer image, i.e., a printed image, obtained through such a conventional thermal transfer recording medium as mentioned above has been disadvantageous because when a sheet of plain paper has been used as a recording sheet, the transferred image has not been clear and sharp unless the surface of the plain paper has been very smooth. As far as this disadvantage is concerned, it may be solved because a relatively sharp dye transfer image may also be reproduced on a sheet of not so smooth paper if a large quantity of thermally fusible materials, coloring agents and the like is added in a coloring agent containing layer. However, the coloring agent containing layer must be thickened as much as they were added, and the resolving power is accordingly lowered. Besides, a fog is caused. The alternatives have been the disadvantage first described and these ones.